Recently, devices have been generally used that file and record video data and/or audio data in a randomly-accessible recording medium (e.g., optical disk, semiconductor memory). For example, in broadcasting stations and video production companies or the like, editing devices including the recording media as described above have been used for a video editing operation. In order to provide the video editing operation as described above, contents data (e.g., video data, audio data) is recorded in a recording medium together with metadata as additional information to these contents. The metadata is used to improve the efficiency of the editing operation for example.
With the background as described above, a method for recording metadata as additional information regarding video data or audio data (material) recorded in a recording medium is disclosed in Japanese Patent Unexamined Publication No. 2001-292411 (hereinafter referred to as “Patent Publication 1”).
In broadcasting stations and video production companies, video and audio or the like (hereinafter may be referred to as “material”) is recorded and these materials are edited and processed to produce a program for broadcasting. The video data and audio data of this program are stored with them recorded in a recording medium. The recording medium is recorded with additional information for identifying the material in detail in the respective processing steps as described above (e.g., the one for recording the material, the one for editing the material, the one for storing the material) and the additional information is used for each processing of the material. The additional information includes metadata. Metadata is data describing, for example, information required for identifying the material obtained through interview or recording (e.g., the time of the recording, the recording ID (IDentifier, identification information), the title of the recording, the name of the cameraman).
As described above, in a recording step for recording the respective pieces of data as material (hereinafter referred to as “material data”) in a recording medium, metadata is recorded together with material data. Metadata added to material is classified into the two types of pieces of metadata as shown below. One type of metadata is metadata previously determined in a planning stage. This metadata includes information showing the times at which video shooting is started and completed, information showing the place of the video shooting (place name), and information showing the cameraman, for example. The other type of metadata is metadata that is generated simultaneously with the video shooting and is recorded in the recording medium. This metadata includes, for example, position information detected by the GPS (Global Positioning System) (e.g., latitude, longitude, altitude), time information, information for the name of a place where the recording is performed, information regarding a machine used for the video shooting (machine ID), information for camera setup (e.g., information regarding lens), UMID Unique Material IDentifier) for identifying the material, and information regarding duration required for the video shooting. The metadata that was recorded together with the material data in the recording medium by the shooting step as described above is associated with the material and is used in subsequent steps. The metadata is a means that is particularly useful for improving the handling and convenience of desired data when the data is searched.
By the way, in an editing step or the like, a time code representing hour, minute, and second of each frame and representing the frame information of the video data is identification information that is very useful when the video data is searched frame by frame in an editing operation for example. Thus, the time code has been conventionally used for a video editing operation or the like. In view of the above, a method has been suggested for editing material using metadata including the data regarding the time code. For example, Patent Publication 1 discloses that a time code showing the start time of each filed material (hereinafter may be collectively referred to as “time” including hour, minute, and second and the information frame by frame that is represented by the frame No. for example). The time code is recorded as metadata generated at the video shooting as described above as the other type. The time code is used as a time code representing each material.
With regards to the addition of the time code to the video data, it has been desired that, in order to provide the search of the video frame by frame while securing the continuity of each frame, the video data is not added with duplicate time codes at the video shooting and the respective materials are provided with continuous time codes. To realize this, in a conventional camera recorder which records data in a magnetic tape medium for example, the recording is generally performed based on a method as described below. In this method, the time code values of tape positions to be recorded are read and the read time code values are given to the video data such that the given time code values are continuous to correspond to the time code values of the tape positions.
However, when a device in which video data is filed and recorded in a randomly-accessible recording medium is used to record new video data by giving, to the new video data, continuous time codes starting from a section next to the last section of already-recorded material in the recording medium, the time codes in the video data of the already-recorded material are not always continuous. The reason is that one video file in the already-recorded material is recorded with recording and pause operations or repeated recording operations, for example. This has caused a possibility that the value of the final time code calculated based on the start time recorded in the time code of the material and the duration for the video shooting does not correspond to the value of the final time code recorded in the video data of the final frame.
Thus, in order to secure the continuity of each frame, the value of the final time code of the already-recorded material must be obtained, thus requiring the scanning of the time codes in the video data file of the already-recorded material. However, when a compression method such as MPEG2 (Moving Picture Coding Experts Group 2) in which video data is encoded by inter-frame compression, streaming, packeting or the like and is recorded is used, the data must be decoded in order to obtain the value of the final time code. This has caused a problem that too much processing time for obtaining the value of the final time code is required and it causes difficulty in securing quick response.
When a user searches desired video data in all materials by specifying the value of a time code of the data, time codes in the video data of all materials must be scanned. This has also caused the problem of an increased processing time.